1. Field of the Invention
The present invention relates to a machine for manufacturing containers, including a system for providing assistance when changing molds.
The present invention relates more specifically to a machine for manufacturing containers which includes at least one molding unit including:                at least two mold holders which are mounted movably between an open position and a closed position of the molding unit, and a mold including at least two molding elements, each of which is fixed removably to one of the mold holders, and        a locking device of the molding unit including at least one control member capable of actuating locking means which are mounted movably between:                    a locked position in which the mold holders of the molding unit are kept in the closed position by said locking means, and            an unlocked position in which the mold holders are freely movable between the closed and open positions.                        
2. Description of the Related Art
In the prior art there are known machines for manufacturing containers, particularly bottles of thermoplastic material, said machines being, notably but not exclusively, of the type known as “rotary”.
FIG. 1 shows by way of non-limiting example a prior art installation 5 including a rotary machine 10 for manufacturing containers, in which installation 5 said machine 10 (also known as a “blow molder”) is notably associated with an oven 12 for the heat treatment of the preforms 14.
The installation 5 includes a device 16 for supplying preforms (or blanks) 14 which are introduced into the installation through an entrance E which communicates with an entrance area of the oven 12.
The oven 12 includes means 18 for heating the preforms 14 which are arranged along all or part of a path, U-shaped in this case, extending from the oven entrance area into which the preforms 14 are guided by the supply device 16 to an exit area of the oven 12, in the vicinity of which a first transfer device 20 is arranged.
The first transfer device 20 is intended to transfer the heat-treated preforms 14 from the exit area of the oven 12 to an area Zi, called the insertion area, for inserting the preforms 14 into the manufacturing machine 10.
The manufacturing machine 10 includes a carousel 22 equipped with a series of circumferentially distributed molding units 24 and with blowing or stretch-blowing means (not shown) associated with said units 24.
The molding unit 24 includes two mold holders 26 which are mounted so as to be movable between an open position and a closed position of the molding unit; for example, when the molding unit 24 is of the “book-like opening” type as shown in FIG. 1, the mold holders 26 (or, in a variant, at least one of them) are mounted rotatably relative to each other about an axis O of rotation.
Each molding unit 24 includes a mold including at least two molding elements 28, each fixed removably to one of the mold holders 26.
In the closed position of the molding unit 24, the molding elements 28 are placed adjacent to each other in such a way that their inner faces form a joint plane, the coupling of the molding half-impressions of each element defining the volume, shape, appearance, and other features of the container to be produced by forming a preform.
A manufacturing machine 10 of this type can operate in different operating modes.
In one operating mode of the machine, called the production mode, the machine 10 is used in combination with the oven 12 of the installation 5 to manufacture containers.
In this operating mode of the machine 10, the carousel 22 is driven in rotation in such a way that each molding unit 24 undergoes a transformation cycle from said insertion area Zi to an area Ze, called the removal area, for the containers 14′, in which a second transfer device 30 is arranged.
The second transfer device 30 is intended to transfer the containers 14′, produced from the preforms 14, from the removal area Ze of the machine 10 to an exit S from the installation 5.
As shown in FIG. 1, the areas for the insertion of the preforms 14 and for the removal of the containers 14′ are adjacent and are located in the front part of the machine 10 in such a way that the transformation cycle takes place over practically the whole circumference of the machine.
The installation 5 generally includes a protective enclosure 31 arranged so as to surround at least the manufacturing machine 10 and the oven 12.
In the production mode of the machine 10 shown in FIG. 1, the manufacturing of containers of plastic material, such as bottles, flasks and the like, is therefore carried out in the molding units 24 by the blow-molding or stretch-blow molding of preforms 14 which have been pre-heated in the heat treatment oven 12.
However, while the production mode is the main operating mode of the machine, the machine 10 also has another operating mode, called the intervention mode, which is equally important.
This is because said at least two molding elements 28 forming the mold and each including one half-impression are fastened to the mold holders 26 by fastening means (not shown) capable of allowing the dismounting and mounting of the elements for the purpose of changing the mold of the molding unit 24.
EP-B1-0.821.641, in the name of the present applicant, describes, notably, various improvements made to the structure of a molding unit 24 and of the mold, and also to the mold fastening means.
This document may advantageously be consulted, although it is cited purely as a non-limiting example.
Such a change of mold is required, in particular, for the purpose of manufacturing containers having different shapes and/or sizes, or for their replacement in case of damage to and/or wear of the molding elements.
The operating mode called the intervention mode, in which the production of containers by the machine is halted, is used more or less frequently, depending on the use of the machine 10.
In some cases, mold changes are very frequent, and therefore the time required to change the mold of a molding unit 24 is the subject of even more attention.
The time required to change a mold has to be multiplied by the number of molding units 24 included in the machine 10, this number being, for example, between 6 and 34 molding units.
The operations required for changing the mold of a molding unit 24 are numerous and are all performed manually by an operator, or in some cases two operators, and therefore the intervention period is often considered excessively lengthy by users, especially if frequent changes have to be made.
This is because the immobilization of the machine 10 during these operations is costly, owing to the complete stoppage of manufacturing which it entails, and consequently the mold changing operations, which are more or less frequent depending on the users, are very costly because they are lengthy and complicated.